1. Field
The disclosed concept pertains generally to electrical switching apparatus and, more particularly, to electromagnetic switching devices, such as, for example, relays and contactors.
2. Background Information
Electromagnetic switching devices are often used to electrically couple a power source to a load such as, for example and without limitation, an electrical motor or other suitable load. An electromagnetic switching device can include both fixed and movable electrical contacts as well as an electromagnetic coil. Upon energization of the electromagnetic coil, a movable contact engages a number of fixed contacts so as to electrically couple the power source to the load. When the electromagnetic coil is de-energized, the movable contact disengages from the number of fixed contacts thereby disconnecting the load from the power source.
In aircraft applications, for instance, electromagnetic switching devices account for a significant portion of the heat generated in aircraft electrical systems and, therefore, may greatly benefit from improved thermal management. For example, for a total voltage drop of 0.175 V for two contact points and a load current of 400 A, the total heat generation is 70 W or 35 W per contact point. The electromagnetic coil is also a source of heat generation. For example, for a voltage drop of 28 V and a holding current of 0.2 A, the total heat generation is 5.6 W.
There is room for improvement in electrical switching apparatus, such as electromagnetic switching devices.